1. Field of the Invention
The present invention relates to conveyor lubricants. More particularly, the present invention concerns the use of combinations of aluminum salts and anionic surfactants as conveyor lubricants. Even more particularly, the present invention concerns conveyor lubricants and concentrates thereof suitable for use with hard water. These conveyor lubricants and concentrates thereof, more particularly, contain aluminum salts, and fatty acids.
2. Description of Relevant Art
In breweries, soft drink bottling operations and food processing plants, conveyors are used to move the bottles, jars, cans and the like along the line. In order to keep the conveyor chains clean and to provide lubrication, it is customary to use a lubricant such as an aqueous soap-based lubricant. The compositions, also, include chelating agents to prevent precipitation of calcium and magnesium soaps. These lubricants are, generally, manufactured and sold as concentrates which must, then, be diluted to, in general, about 1:100 with tap water at the point of use.
There has been a constant search for greater lubricity in such compositions. It can readily be appreciated that increased lubricity will be highly advantageous in that it will aid movement of the units along the conveyor lines and prevent wear on both the units to be moved and the line itself.
Various additives have been proposed in compositions to aid and enhance lubricity. Fatty acids and various soaps have been employed in such compositions. However, fatty acid lubricants have not been readily adopted as additives for a variety of reasons.
Furthermore, while the art has readily accepted the use of water-soluble soaps as lubricants, they too, have certain disadvantages. First, when a soap is dissolved in hard water, it will precipitate as the calcium or magnesium salt of the fatty acid. This precipitation problem is further aggravated if free fatty acids are present in the lubricant. The precipitate thus formed creates an undesirable greasy-type film. This film is difficult to remove and attracts dirt, dust and grime; all of which are highly undesirable in food handling equipment.
In order to overcome these disadvantages, various lubricant compositions have been proposed. In U.S. Pat. No. 4,604,220 to Stanton, the use of anionic surfactants selected from the group consisting of C.sub.12 to C.sub.18 alpha olefin sulfonates and mixtures thereof in lubricant concentrates. This addition resulted in improved lubricity on conveyors handling aluminum containers. However, such lubricant concentrates and compositions are significantly less effective with conveyors handling glass containers or containers manufactured from polymers such as polyethylene terephthalate than other conventional lubricants.
Additionally, conveyor lubricants such as those disclosed in the Stanton reference do not exhibit high levels of hard-water stability.
Thus, it is desirable to provide a lubricant concentrate and lubricant composition which provide enhanced lubricity; particularly when conveying glass or PET containers. It is also desirable to provide a lubricant concentrate and composition which are highly stable in the presence of hard water.